Charged particle multiplicities in heavy and light quark initiated events above the Z° peak

We have measured the mean charged particle multiplicities separately for b (b) over bar, c (c) over bar and light quark (u (c) over bar, d (d) over bar, s (s) over bar) initiated events produced in e(+)e(-) annihilations at LEP. The data were recorded with the OPAL detector at eleven different energies above the Z(0) peak, corresponding to the full statistics collected at LEP1.5 and LEP2. The difference in mean charged particle multiplicities for b and light quark events, delta(bl), measured over this energy range is consistent with an energy independent behaviour, as predicted by QCD, but is inconsistent with the prediction of a more phenomenological approach which assumes that the multiplicity accompanying the decay of a heavy quark is independent of the quark mass itself. Our results, which can be combined into the single measurement delta(bl) = 3.44 +/- 0.40(stat) +/- 0.89(syst) at a luminosity weighted average centre-of-mass energy of 195 GeV, are also consistent with an energy independent behaviour as extrapolated from lower energy data. (C) 2002 Elsevier Science B.V. All rights reserved.